The reason for the tribe's name “Blackfoot” is because they blackened their moccasins with ash to distinguish themselves from other tribes. This is what is believed to be the history.
Also, there is a difference between Blackfoot and Blackfeet. The Blackfoot are in Canada and the black feet are in the United States. in the Blackfoot language Siksika means “Blackfoot”. The Blackfoot tribe speaks Algonquian language, traditionally the same as the Kaini (Blood Tribe) and Piikani (Piegan Tribe)